geologic
This is another view from the north section of T Roosevelt NP. We were on a ridge looking down into eroded sections of the Little Missouri River valley. You can see the effects of uplifting and erosion as well as gray bentonite clay (old deposits of volcanic ash) - which can hold huge amounts of water and flows when it is saturated. There is also a capstone, created when harder rock doesn't erode as fast as the softer stone below it, which leaves a cap on a pillar. Finally, there is a very large petrified tree trunk revealing itself as the sandstone around it erodes.
geologic
This is another view from the north section of T Roosevelt NP. We were on a ridge looking down into eroded sections of the Little Missouri River valley. You can see the effects of uplifting and erosion as well as gray bentonite clay (old deposits of volcanic ash) - which can hold huge amounts of water and flows when it is saturated. There is also a capstone, created when harder rock doesn't erode as fast as the softer stone below it, which leaves a cap on a pillar. Finally, there is a very large petrified tree trunk revealing itself as the sandstone around it erodes.